Rounding of nearest 0.5

Question

I want to be rounded off this way

13.1, round to 13.5
13.2, round to 13.5
13.3, round to 13.5
13.4, round to 13.5
13.5 = 13.5
13.6, round to 14.0
13.7, roun         


        

Answer 1

If it is required for 13.1, round to 13.5 and 13.9, round to 14.0, then:

double a = 13.1;
double rounded = Math.Ceil(a * 2) / 2;